The commercial and personal grilling markets have blossomed over the past few years. Numerous high-end charcoal or wood burning grills have been designed and introduced to the market. Perhaps the most popular style of grills being introduced to the market is the ‘kamado’ style grill which is a modernization of a traditional Japanese wood or charcoal fueled cook stove. The industry regards these grills as notably different from other types of grills in terms of their functionality, versatility, style, and the science behind these cooking apparatus. As such, they are markedly distinct from other types of charcoal grills.
A traditional “kamado” is a Japanese wood or charcoal fueled cook stove. Modern kamado style cookers are made from a variety of materials including high fire ceramics, refractory materials, double wall insulated steel, traditional terra cotta, and a mix of Portland cement and crushed lava rock. Most commonly, the modern kamado style grill is typically formed out of a thick layer of ceramic materials. The use of ceramic in kamado stoves has been known and used for centuries primarily in Japan because ceramic is capable of efficiently absorbing and holding heat at both high and low temperatures for extended periods of time. These properties allow the kamado style grills to be versatile in that they can be used for both smoking meats, which is typically performed in the range of 225-275 degrees for numerous hours, baking and broiling, and for grilling at much higher temperatures of 450 degrees or higher. The heat chamber of a kamado grill is generally elongated such that a heat defector can be placed between the heat source and the dome lid, creating a convection oven effect in the cooking chamber.
The unparalleled versatility of kamado style grills is perhaps the most notable difference between kamado style grills and their traditional counterparts. Whereas traditional grills are limited to either high temperature grilling devices or low temperature smokers, the engineering of kamado style grills allows them to cook at the full spectrum from low and slow smokes to grilling at temperatures of 800 degrees or more. Most importantly, the engineering allows for these temperatures to be controllably reached and maintained for long periods of time. For this reason, kamado style grills are regarded as distinct from their traditional grilling and smoker counterparts known throughout the bar-b-que industry.
The efficiency of the modern kamado style grill design can perhaps best be exhibited in its ability to obtain and hold temperatures using low fuel amounts (i.e., smaller amounts of charcoal and wood than a typical grill or smoker). The efficiency lies in the insulation, often provided by ceramic materials in conventional kamado grills. The insulation of a ceramic kamado cooker retains and radiates heat back into the cooking chamber, meaning that less charcoal and oxygen are required. Those skilled in the art recognize that the airflow causes meat to dry out; thus, kamados are typically well suited for long smokes of big pieces of meat.
For example, when smoking a pork shoulder, it is generally accepted that the meat should be smoked ‘low and slow’ at a temperature of 225 degrees. Although the time will vary from cook to cook, a general estimate is that the meat has to be smoked for 1-1.5 hours per pound, meaning that a 10 pound pork shoulder will be smoked for roughly 10-15 hours before it reaches the desired internal temperature of 195 degrees, which is the generally accepted minimum temperature for the collagen and fibers in pork to have broken down for pulled pork.
In a typical smoker, fuel will have to be routinely introduced to maintain temperature at a steady 225 degrees. Every time any cooking chamber is opened to introduce more fuel, temperature is lost and becomes unbalanced, leading to uneven cooking. Such actions can affect the cooking process in many ways. For example, when the cooking chamber opens, the moisture released from the meat is able to escape from the confines of the grill dome and is lost to the ambient atmosphere. Worse still, ambient air is also able to enter into the system. Because airflow is one of the leading causes of dry meat, the entry of ambient air can directly impact the dryness of the item being cooked. Additionally, the uncontrolled influx of oxygen into the cooking chamber will stoke the fire, causing the flame system to become unbalanced. These problems are further compounded in nearly all non-offset smokers because the meat has to be removed entirely from the smoker in order to access the location where the fuel is to be introduced. Actual offset smokers likewise suffer their own deficiencies.
However, the kamado style grill is capable of maintaining temperature using low amounts of fuel exposed to a controlled, minimum flow of oxygen; therefore, it is often possible to conduct a full 10-15 hour (or longer) smoking process using only the fuel initially introduced into the grill. This type of temperature control is generally reserved for gas and propane grills which are not suited for smoking meats because of the lack of smoke flavor and difficulty in introducing the flavors. But, ceramic kamado style grills, such as the grills available from Big Green Egg® and Primo® Grills and Smokers, have shown such efficiency because they have low heat loss and fuel usage. (BIG GREEN EGG is a registered trademark of Edward R. Fisher, and PRIMO is a registered trademark of Primo Ceramics, L.L.C.). Because the smoking process is capable of being conducted without the need to introduce additional fuels during the smoke, the food cooked in these kamado style grills to retain its moisture and oils.
The true versatility is perhaps best exhibited in the kamado's ability to perform a ‘reverse sear’ method to cook larger pieces of red meat such as prime ribs. Basically, the notion of the reverse sear is to cook the meat low and slow indirectly at a lower temperature such as 250 degrees until it reaches a desired temperature, and then to raise the temperature significantly to around 400-600 degrees in order to give the meat a seared crust. By comparison, using traditional cooking methods, a prime rib is typically cooked in an oven at 400 degrees until the desired temperature. This method causes a large amount of the meat's juice to release from the meat and collect in the pan. In order to prevent the waste of these juices, an au jus is typically created using the drippings as a base and is served alongside the meat. On a kamado style grill, it is possible to cook the meat with a reverse sear method so that the juices are not released in the first place. To cook a prime rib under this method, the kamado style grill is set up to cook indirectly at a lower temperature such as 250 degrees. The meat is introduced onto the kamado style grill and is uniformly cooked or smoked until it reaches a desired temperature, typically about 115 degrees if medium rare is ultimately desired. Once the meat is at the desired internal temperature, it can be removed and the kamado style grill can be adjusted by opening the flue system to cook directly at a higher temperature. For example, it is common in such a method for the temperature of the kamado style grill to be heated to 400-600 degrees by increasing the flow of oxygen into and exhaust out of the cooking chamber. Once at the desired temperature, the meat is reintroduced and seared on all sides to form a crust that traps the juices while raising the internal temperature to the desired doneness. Using this method, the juices typically do not leak out of the meat in noticeable quantities because the meat is only exposed to high temperatures for short periods.
It is clear that kamado style grills demonstrate great benefits and versatility which put them in a separate class from other grills. But despite the obvious benefits over traditional grills and smokers, the kamado grills available in the market place suffer serious deficiencies. The vast majority of kamado grills comprise heat tolerant and absorptive ceramic materials, which generates some of the best qualities of these kamado style grills. However, the ceramic itself introduces numerous drawbacks, particularly in terms of its durability as ceramic materials are prone to chipping, cracking, crazing, and shattering. While ceramic may be a good insulator of heat, it is not very tolerant to quick changes in heat, and such exposure has been known to cause the ceramic to crack. The greatest danger to cracking is through contact with external forces which generally prevents the grills from being portable. Typically, the kamado style grills are permanently situated in a housing such as a grill table or cart to minimize exposure, but even such measures pose a risk as kamado style grills are sometimes dropped or damaged during or after the mounting stage into these tables or carts. Still, the grills are commonly damaged during shipping and transportation, even when painstakingly packaged. Such issues have prevented many third party retailers from selling these products on-line as they would have to ship the products to consumers, risking damage that would not be covered by the manufacturer.
Ceramic products also suffer from the drawback that they cannot be modified once casted. Because the typical kamado style grill is shaped from a single ceramic mold, it is nearly impossible or, at least, very risky to drill any holes into the ceramic shell for mounting of any components. This leads to additional drawbacks which are evidenced in numerous kamado style grills. For example, it is a given that the grill top or lid must be separable from the base in order to access the interior of the cooking chamber and the food being cooked. To accommodate this separation, tension spring hinges are often employed to connect the top (lid) and base structures such that the top can be manipulated on the hinge so as to separate from the base. However, the hinge cannot be directly attached to the top and base because the kamado style grill components cannot be drilled or threaded for screws. Additionally, even if a certain location of the ceramic would be capable of being drilled, the unitary ceramic structure would still lack the necessary tensile strength to account for the stress of pivoting the top lid. Thus, the industry has turned to external bands that are pressure fit around the entirety of the top and base structures which in turn is mechanically connected to the hinge. Effectively, the external pressure fit bands indirectly attach the hinge to the components and distribute the weight around the entire structures. In practice, this can cause several issues. First, it requires a great deal of adjusting to align the external pressure fit bands properly to create a good seal. Proper alignment is instrumental as the kamado style grill requires precise oxygen control to maintain balanced heat; therefore, even a slight gap or misalignment can throw off the efficiency of the grill. Second, the pressure nature of the external pressure fit bands causes tension to be exerted on the ceramic, which can in turn cause chipping, cracking, or even structural damage that would impede the use of the grill. It is nearly impossible to safely ship the units assembled without damaging the grill. Thus, it is routinely an untrained end user who installs these external pressure fit bands, not a trained professional such as the manufacturer, further compounding these issues. This creates ample opportunity for the end user to improperly install the external pressure fit bands, causing the components to be imbalanced impeding a proper cook, or otherwise break.
The use of external pressure fit bands often results in a less than perfect seal between the top of the grill and the base. In order to compensate for this gap, gaskets of felt-like Kevlar are typically applied to the open edge of the top and base. Therefore, when the top is down in the closed position, the gaskets will come into contact with each other and create a seal. However, because these gaskets are exposed to high temperatures, they often wear out over time and are susceptible to being scorched and will have to be replaced, increasing operating expense that will compound over time.
The external pressure fit bands also suffer from intrinsic design faults themselves. To support the weight of the top unit, the bands are typically constructed from hard metals such as iron and steel. While these metals may be well-suited to support the load of the top lid, they are prone to rusting when exposed to elements. Thus, as grill components, which are almost always exposed to the ambient atmosphere and often to precipitation, the bands will rust overtime and need to be replaced. This is particularly troublesome in marine environments where the bands may be exposed to saltwater. If not replaced, the bands may be prone to mechanical failure that can result in a damaged or broken grill.
As previously indicated, ceramic kamado style grills are not easily transported, particularly after initial delivery and setup. Therefore, they are usually mounted into carts and tables where they will be used. Many grill tables are made out of wood which obviously poses a risk of combustion when in contact with a high temperature kamado style grill for extended periods of time. Air and cement are typically used to dissipate the heat so as to help prevent a fire. In order to create a cushion of airflow below the kamado style grill, the grill is generally raised and propped up via “feet” components that are made of temperature resistant material, such as ceramic or concrete, which allow for a cushion of air to flow underneath the base and dissipate heat. Additionally, the kamado style grill can be propped on cement blocks which will dissipate the heat to a degree that it will not cause combustion. Even these safety features pose additional risks to the grills themselves and to the surrounding areas. There exists no way to securely attach the grill to the feet or cement blocks because the grill chassis cannot be tapped or drilled into. Therefore, while external components can be used to aid in fire prevention, they do so in a less than secure manner that introduces the risk that the kamado style grill would tip over, cracking the ceramic or starting a fire.
Attempts have been made in the past to provide a kamado style grill made out of materials other than just pure ceramic, but they too exhibit their own issues. These attempts demonstrate a hybrid-ceramic kamado style grill with dual layers of materials that often involves double wall insulated steel which houses an insulating component between the steel walls. For example, Caliber Range Corporation offers a ThermaShell Pro Grill kamado style grill which uses a double layer of 304 grade stainless steel enclosing a layer of ceramic insulation. Although an improvement in many ways, this design also exhibits a number of problems. The ceramic insulation may be housed within stainless steel casings, but the very existence of ceramic is a weakness to the design as it remains prone to cracking and breaking. Additionally, while the stainless steel can be drilled or tapped, the ability to do so is limited because it can only be done in gaps in the ceramic. This means that areas must exist in the construction of the kamado style grill does not have the ceramic insulating layer. This limits the efficiency of the grill to maintain and hold heat, and also reduces the ability to modify the location of the drillings as may be necessary for customizing the kamado style grill. Also, the stabilizing devices such as feet would most likely be attached to the bottom, an area that must be insulated as it is likely to contact fallen embers. In effect, the drill locations have to be specifically considered in the design, limiting the ability to customize the kamado style grill at any time after production. Also, the manufacture of this design requires multiple additional steps and components which are not typically required in the creation of a ceramic kamado style grill but are required to line up and create the layered unit, increasing the manufacturing costs.
Accordingly, there exists a strong need for a durable kamado style grill that is capable of harnessing the versatility and cooking abilities of the traditional and modern kamado style grills while solving the deficiencies noted in kamado style grills sold and used today.